With the purpose of ecological environmental safety, every industrial enterprise shall strive, on the one hand, for a maximum reduction of fresh water consumption by using it repeatedly in the technological process and, on the other, for the greatest degree of purification of the contaminated industrial sewage discharged into the environment. The repeated utilization of industrial water in the technological process calls for its continuous or periodical purification to the state of clarity. Widely used nowadays in industrial practice for clarification of industrial sewage mainly containing fine suspended solid particles are thickeners, settlers and clarifiers. Intensification of technological processes involving the use of industrial waters and purification of contaminated industrical sewage containing fine suspended solid particles calls for a continuous improvement of the capacity and efficiency of the thickeners and clarifiers used.
Intensification of clarification of such sewage is usually achieved by the use of high-molecular flocculants. In the course of sewage clarification the fine solid particles settling in the form of floccules form a steady three-dimensional structure which interferes with unloading of slurry from purifying apparatuses and causes frequent breakdowns of the slurry unloading mechanism in the thickeners. Therefore, the apparatuses for clarification of industrial sewage usually incorporates either mechanisms for mechanical destruction of such a three-dimensional structure in the course of unloading of the slurry from the apparatus or devices for its destruction with jets of liquid.
The use of high-molecular flocculants for clarification of industrial sewage containing surfactants in the form of flotation reagents and, particularly, foam generators, conduces to the formation of floccules containing gas-air, oil-like and inorganic components which reduces their precipitation rate and, consequently, capacity of apparatuses. This is caused by the fact that the movement of industrial sewage containing surfactants and organic and inorganic substances is accompanied, as a rule, by formation of gas and air bubbles therein. This is caused by ejection of air during turbulent action of the liquid. The higher the concentration of these surfactants in the liquid the greater is its saturation with gas and air bubbles in motion. The liquid is most intensively saturated with gas bubbles by changes in the direction of its flow and jet-type ejection inevitable during transportation of industrial sewage to the clarification apparatuses and when it passes directly through the apparatuses. The gas bubbles in the polluted industrial sewage interferes with its intensive clarificiation because the gas bubbles coming to the surface in the clarification zone carry the slimy particles to the layer of clarified water due to their flocular flotation and turbulent mixing. The presence of gas-air, oily and some inorganic components in the industral sewage makes the formed floccules loose, light and easily floatable which reduces their precipitation rate and, as a consequence, impairs the efficiency and capacity of clarification of industrial sewage.
Known in the prior art is an apparatus for clarification of industrial sewage (SU, A, 1351674) comprising a vertically-installed cylindrical chamber for circulation of industrial sewage said chamber having a cone-shaped bottom comprising a branch pipe for feeding in the polluted industrial sewage with flocculants, the outlet hole of said branch pipe being arranged along the axis of the cylindrical chamber for circulation of industrial sewage, and a branch pipe for discharging the slurry, a circular trough for draining the purified industrial sewage secured on the outside of the sewage circulating chamber at its upper edge, and partitions accommodated in said circulating chamber for settling of solid particles, the surfaces of said partitions being inclined towards the axis of the cylindrical sewage-circulating chamber, and at least one separating partition in the form of a body of revolution with holes intended for distributing the polluted sewage over the volume of the circulating chamber, said separating partition being installed along the axis of the sewage circulating chamber, in its central part.
In said sewage clarification apparatus the separating partition is arranged, essentially, along the height of the cone-shaped bottom, its upper edge is arranged somewhat higher than the joint between the cone-shaped bottom and the cylindrical part of the chamber. The apparatus also comprises two groups of partitions for settling of solid particles consisting, each, of a set of conical coaxially installed shells. One group of conical shells is installed in the cone-shaped bottom and the other one, in the cylindrical part of the chamber, between its upper edge and the upper edge of the separating partition. In said other group of concial shells their bases of a smaller diameter are directed to the upper edge of the cylindrical sewage-circulating chamber.
Such an arrangement of the separating partition and of the parititions for settling of solid particles creates a conical zone above the upper edge of the separating partition, said zone tapering towards the upper edge of the cylindrical sewage-circulating chamber which offers resistance to the flow of gas-air bubbles liberated from the delivered polluted industrial sewage and conduces to the formation of floccules with a gas phase which, in the long run, impairs the capacity of the apparatus for clarification of industrial sewage, the efficiency and quality of its purification.
Another previously known apparatus for clarification on industrial sewage (SU, A, 1178464) comprises a vertically-installed cylindrical sewage-circulating chamber with a cone-shaped bottom secured on which is a branch pipe for feeding in polluted sewage with flocculants whose outlet hole is arranged along the axis of the cylindrical sewage-circulating chamber, and a slurry-discharging branch pipe, a circular trough for draining the purified sewage secured on the outside of the cylindrical sewage-circulating chamber, at its upper edge, and partitions accommodated inside the cylindrical sewage-circulating chamber, for settling of solid particles, the surfaces of said partitions being inclined towards the axis of the cylindrical sewage-circulating chamber, and at least one separating partition in the form of a body of revolution with holes for distributing the polluted industrial water over the volume of the cylindrical sewage-circulating chamber, installed along the axis of said chamber in its central part, the upper edge of said partition being aranged, essentially, level with the upper edge of the cylindrical sewage-circulating chamber.
In said apparatus for clarification of industrial sewage the separating partition is installed along the entire height of the chamber to the level of its upper edge and the gas-air bubbles are liberated in a natural way, from the surface of the sewage in the chamber. The partitions for settling of solid particles in the form of conical shells whose large-diameter bases face the upper edge of the sewage-circulating chamber do not offer any resistance to the flow of gas-air bubbles. However, in the course of natural liberation of gas-air bubbles from the surface of the sewage continuously delivered into the chamber at least 50% of its gas component participates in the formation of floccules with a gas phase, i.e. floccules which retard the precipitation of solid particles which, in the long run, reduces the capacity of the sewage purification apparatus, impairs the efficiency and quality of purification.
An object of the invention lies in raising the capacity of the apparatus for clarification of industrial sewage, the efficiency and quality of sewage purification.